Gold that is found in placer deposits in the form of fine grains or flakes is extracted by a process called goldpanning. It is a simple and ancient way of removing gold and is cheap too. The pan used is a shallow one and is measured in inches by its diameter. Pans range from 10″ to 14″ in size and come in both metal and plastic. They have a means for trapping the heavy elements when they are agitated. In goldpanning, the material is filled along with water and is shaken in a steady way to make the gold and other heavy elements at the bottom and the lighter elements which are unwanted are thrown away. Native gold also appears in the form of nuggets which can also be separated easily as they are easily visible to the eye.
Gold ore is found as amalgam which is a combination of gold and mercury or as electrum which is its combination with silver. In either case, a chemical process is used for removing the gold from such ores. Some gold is also found embedded in hard rocks in the form of fine particles. For extraction, gold panning can be done and also froth flotation is used for concentrating the gold.
Some of the gold ores contain sulfide minerals in larger quantities and here a chemical process of froth flotation has to be done. Ore smelting is performed for removing the pure gold from its ore and here the process that takes place is called reduction of the metal, whereby electrons are removed. This process is just the reverse of oxidation, but it is more than just melting of the ores.
A non metal oxide waste called slag is formed. The gold ore smelting first involves crushing and milling the gold into dust and then it is classified by sizes. If the gold is present in the form of very fine particles and is not well liberated from the parent rock, then the concentrates are treated with a chemical process of cyanide salts which is also called cyanidation leaching and then recovered.
The gold dust is then melted in a furnace along with a chemical flux. A slag which contains all the other metals in it such as copper, zinc and iron is formed and this can be removed. What is left behind is pure gold and this is formed into bars. Direct smelting is also possible.
Some of the gold ores contain sulfide minerals in larger quantities and here a chemical process of froth flotation has to be done. Ore smelting is performed for removing the pure gold from its ore and here the process that takes place is called reduction of the metal, whereby electrons are removed. This process is just the reverse of oxidation, but it is more than just melting of the ores.
A non metal oxide waste called slag is formed. The gold ore smelting first involves crushing and milling the gold into dust and then it is classified by sizes. If the gold is present in the form of very fine particles and is not well liberated from the parent rock, then the concentrates are treated with a chemical process of cyanide salts which is also called cyanidation leaching and then recovered.
The gold dust is then melted in a furnace along with a chemical flux. A slag which contains all the other metals in it such as copper, zinc and iron is formed and this can be removed. What is left behind is pure gold and this is formed into bars. Direct smelting is also possible.
No comments:
Post a Comment